1. Field of the Invention
The present invention relates to reinforcing bamboo fibers, a method of producing the reinforcing bamboo fibers, an inorganic molded body using reinforcing bamboo fibers, and a method of producing the inorganic molded body.
2. Description of the Prior Art
For production of a wood-based inorganic molded body, as a rule, a woody raw material, i.e., processed wood article such as wood flakes, excelsior and wood fibers, an inorganic hydraulic setting bonding agent such as various types of cement, hydraulic setting gypsum, and water are mixed and kneaded, before being formed into a given shape and subsequently cured and hardened.
For making the woody raw materials, various kinds of conifers and broad-leaved trees have come into widespread use, while bamboo materials have also been proposed as being used for the woody raw materials. Bamboo materials are full of promise as a resource, for bamboo grows faster than the conifers and broad-leaved trees. In addition, bamboo materials are also more desirable as the woody raw material because of their toughness and elasticity. However, bamboo has heretofore been used only in the form of bamboo fibers substituted for wood fibers or wood flakes, which does not sufficiently demonstrate the toughness and elasticity features of bamboo materials.
The present inventors have developed a technique to use a bamboo material as a woody raw material for a wood-based inorganic molded body, and more particularly a method of producing a wood-based inorganic board wherein a woody raw material, an inorganic hydraulic setting bonding agent and water are mixed and kneaded, before the resultant mixture is formed into a given shape and subsequently the inorganic hydraulic setting bonding agent is cured and hardened.
Japanese Patent Laid-Open No. 2-26854 discloses a method of production wherein the bamboo material absorbs water to reach a moisture content more than 100% before undergoing a dehydration process to reduce water content more than 50%.
In addition, Japanese Patent Laid-Open No. 2-48446 discloses a method of producing a wood-based inorganic board wherein a woody raw material, an inorganic hydraulic setting bonding agent and water are mixed and kneaded before the resultant mixture is formed into a given shape and subsequently the inorganic hydraulic setting bonding agent is cured and hardened, which is characterized by using, as a woody raw material, wood fibers or wood flakes subjected to epidermis removal.
The techniques as disclosed in these patent applications have been developed with a view to improving compactibility coupled with preventing spring back in production of the inorganic board including the bamboo fibers as the raw material, but not towards making the most of the toughness and elasticity of the bamboo materials.
Moreover, Japanese Patent Laid-Open No. 4-46046 discloses a wood-based inorganic molded body obtained through processes in which a woody raw material, an inorganic hydraulic setting bonding agent and water are mixed and kneaded, before the resultant mixture is formed into a given shape, then cured and hardened. More specifically, this application discloses a bamboo fiber reinforced inorganic molded body characterized in that the woody raw material comprises fibers obtained by defiberizing a bamboo material in the longitudinal direction and having an average length of above 20 cm and an average diameter of below 3 mm, and further discloses a bamboo fiber reinforced inorganic molded body characterized in that the woody raw material comprises fibers obtained by defiberizing a bamboo material in the longitudinal direction and including more than 60% by dry weight of long-fiber components whose lengths are above 20 cm and whose average diameter is below 3 mm and more than 5% by dry weight of short-fiber components whose lengths are below 1 cm and whose average diameter is below 2 mm.
Japanese Patent Laid-Open No. 4-216007 discloses a bamboo fiber manufacturing method comprising a first step of roughly crushing a bamboo material with a rolling machine in a bamboo growing direction and a second step of feeding the bamboo material processed in the first step through feeding rollers into a defiberizing apparatus equipped with a rotary drum having a number of toothed portions so as to defiberize the bamboo material.
Japanese Patent Laid-Open No. 5-138617 discloses a bamboo fiber manufacturing method comprising a first step of roughly crushing a bamboo material with a rolling machine in a bamboo growing direction, a second step of defiberizing the bamboo material processed in the first step with a pickering machine, and a third step of thinning the bamboo material processed in the second step with a turbo mill.
Japanese Patent Laid-Open No. 6-15616 discloses a bamboo fiber manufacturing method comprising a first step of roughly crushing a bamboo material with a rolling machine in the direction of bamboo growth, a second step of fiberizing the roughly crushed material processed in the first step using a hammermill type grinder with a specific mechanism, and a third step of separating inner thin skin portion of the bamboo material, from the fibers obtained in the second step.
When the bamboo fiber reinforced inorganic molded body is actually manufactured using the bamboo fibers produced in accordance with the methods noted in the foregoing patent applications, it has been found that performance can deteriorate to a considerable extent with the passage of time.
In addition, Japanese Patent Laid-Open No. 6-315908 discloses a method of modifying the quality of a raw woody material by using a drying-by-heating quality-modifying furnace. This method comprises the steps of: making a loop of green wood such as lumber or bamboo with a large moisture content and, if needed, additionally processing it to make a processed article, such as a half-processed article or a formed article; and subsequently drying and quality-modifying the article in the drying-by-heating quality-modifying furnace so that the article develops a given degree of drying corresponding to 3 to 16% moisture content and so that various components other than moisture originally contained in the green wood are evenly distributed into all tissues.
Japanese Patent Laid-Open No. 6-315912 also discloses a method of modifying the quality of a raw woody material by using a drying-by-heating quality-modifying furnace. This method is composed of the steps of: making a loop of green wood such as lumber or bamboo with a large moisture content and, if needed, additionally processing it to make a processed article, such as a half-processed article or a formed article; and subsequently drying and quality-modifying the article in the drying-by-heating quality-modifying furnace so that the article undergoes a given degree of drying corresponding to 15 to 25% moisture content and so that various components other than moisture originally contained in the green wood are evenly distributed into all tissues.
These patent applications suggest techniques to adjust the moisture content of bamboo materials, but do not teach any detailed embodiment related to the moisture adjustment of the bamboo material or any detailed effects exhibited. In addition, these patent applications do not teach or suggest the method of adjusting moisture content and the effects demonstrated.